title: Virus capsid expansion driven by the capture of mobile surface loops.
abstract: The capsids of tailed-DNA bacteriophages first assemble as procapsids, which mature by converting into a new form that is strong enough to contain a densely packed viral chromosome. We demonstrate that the intersubunit crosslinking that occurs during maturation of HK97 capsids actually promotes the structural transformation. Small-angle X-ray scattering and crosslinking assays reveal that a shift in the crosslink pattern accompanies conversion of a semimature particle, Expansion Intermediate-I/II, to a more mature state, Balloon. This transition occurs in a switch-like fashion. We find that crosslink formation shifts the global conformational balance to favor the balloon state. A pseudoatomic model of EI-I/II derived from cryo-EM provides insight into the relationship between crosslink formation and conformational switching.
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Kelly K
authors.initials: KK
authors.lastname: Lee
authors.forename: Lu
authors.initials: L
authors.lastname: Gan
authors.forename: Hiro
authors.initials: H
authors.lastname: Tsuruta
authors.forename: Crystal
authors.initials: C
authors.lastname: Moyer
authors.forename: James F
authors.initials: JF
authors.lastname: Conway
authors.forename: Robert L
authors.initials: RL
authors.lastname: Duda
authors.forename: Roger W
authors.initials: RW
authors.lastname: Hendrix
authors.forename: Alasdair C
authors.initials: AC
authors.lastname: Steven
authors.forename: John E
authors.initials: JE
authors.lastname: Johnson
mesh_terms: D036022:Capsid Proteins / Q000737:chemistry* / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D009068:Movement; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D014771:Virion / Q000737:chemistry / Q000378:metabolism; D019065:Virus Assembly / Q000502:physiology*
chemical_list: D036022:Capsid Proteins; D046912:Multiprotein Complexes